DISTRIBUTION OF THE RAINFALL. 287 



To allay suspicions and fears which may arise in some minds, but 

 which I consider groundless and unnecessary, I may state that the 

 underlying question does not relate to the existence of what may be 

 called a personal Creator, though that question may legitimately be 

 engrafted upon it ; but it relates solely to the mode of creation — the 

 wonderful workings of the Creator in clothing the earth with diversi- 

 fied forms of vegetation ; and further, that it takes not up the 

 question of evolution and development, which has disturbed many 

 of the Christians of our day — as did the discovery of the earth's 

 motion, by Galileo, disturb many of the Christians of his day, — but 

 it takes up only the question of the distribution of existing species of 

 plants, in whatsoever way these have been produced. 



We do not find the pear mould growing on the cheese, nor the 

 cheese mould on the orange, nor the orange mould on either. Each is 

 confined to it own habitat. Neither do we anywhere find all kinds of 

 plants growing intermixed on the same bank. In diff"erent places we 

 may find many different kinds of plants growing intermixed, but the 

 plants so intermixed in their growth are different in different places. 



There are some plants which are widely distributed. With others 

 it is otherwise, they are confined each to some one locality. Of the 

 former, we have examples in the silver weed (Potentilla anserina), 

 in the goosegrass or cleavers (Galium aperine), in the square-stalked 

 willow herb ( Eiyilohiiiin tetragonum), in the water starwart (Calitriche 

 verna), and in the daisy (BelUs perennis); of the latter, we have 

 examples in the Scottish primrose (Primula Scottica), which is found 

 only in the north of Scotland and the Orkneys, in the Pride of 

 Table Mountain (Disa grandiflora), which is found only on the 

 mountain at the Cape of Good Hope, whose name it bears, and in the 

 Kerguelens-land cabbage (Pringlea antiscorhiitica), which is found 

 growing on an island most remote from any continent, and which, 

 besides this esculent, yields only seventeen other flowering plants. 



Again there are some plants which you never find excepting near 

 the sea ; others which you never find excepting on marshy ground ; 

 others which you never find but in Alpine regions. There are some 

 plants which are never found growing wild excepting in the tropics, 

 and others which cannot be reared there even hy artificial culture. 

 There appear to be, at least, three determining conditions of the 

 distribution of plants : heat, moisture, and soil. I say, at least three, 

 for I think there are others, such as atmospheric pressure, &c. ; and 

 the modifications of these three, and the combinations of these 



